Colorectal cancer, also referred to as colon cancer or large bowel cancer, is a malignant neoplastic disease associated with tumors in the colon, rectum and appendix. With 655,000 deaths worldwide per year, it is the third most common form of cancer and the second leading cause of cancer-related death in the Western world.
Colorectal cancers originate in the colorectal epithelium and typically are not extensively vascularized (and therefore not invasive) during the early stages of development. The transition to a highly vascularized, invasive and ultimately metastatic cancer, which spreads throughout the body, commonly takes ten years or longer. If the cancer is detected prior to invasion, surgical removal of the cancerous tissue is an effective cure. However, colorectal cancer is often detected only upon manifestation of clinical symptoms, such as pain and black tarry stool. Generally, such symptoms are present only when the disease is well established, often after metastasis has occurred, and the prognosis for the patient is poor, even after surgical resection of the cancerous tissue. For example, patients diagnosed with early colon cancer generally have a much greater, five-year survival rate as compared to the survival rate for patients diagnosed with distant metastasized colon cancer. Accordingly, early detection of colorectal cancer is of critical importance for reducing its morbidity.
Diagnostic methods for colon cancer most frequently depend on direct visual inspection of the gastrointestinal (GI) tract. Endoscopy involves inspection with a miniaturized light source at a probe end of a coherent bundle fiber optic cable. Reflected light beam images are returned through the fiber optic cable for detection by an external digital camera and display on an external monitor or for recording on an external video recorder or both. While this technique allows for identification, removal, and biopsy of potentially cancerous growths such as polyps, its use is associated with certain disadvantages, such as being expensive, uncomfortable, inherently risky due to its invasive nature, and the inability to access some portions of the large intestine and most of the small intestine.
Swallowable endoscopy capsules containing miniaturized optical, digital camera and radio transmission systems have been subsequently developed along with complementary external monitoring systems for inspecting the GI tract. For example, the capsule marketed under the trade name PillCam® SB was initially approved by the U.S. Food and Drug Administration in 2001 for detection and diagnosis of disorders of the small intestine. U.S. Pat. No. 5,604,531 discloses an in vivo video camera system comprising a swallowable capsule. The transit of endoscopy capsules through the small intestine is dependent on peristalsis, meaning that some areas with lesions may be missed if the capsule is not retained in that area for a sufficient amount of time. Further, the endoscopy capsules in current use are not capable of identifying molecular markers, which may be early indicators of colorectal cancer, even prior to the development of pre-cancerous polyps.
U.S. Pat. No. 7,468,044 discloses a system and method for in vivo and in situ detection of body lumen conditions, such as in the GI tract. The system comprises an interaction chamber comprising an indicator; a light source for illuminating the interaction chamber; and an optical detector for detecting in vivo optical changes occurring in the interaction chamber upon reaction of the indicator with an endo-luminal sample.
U.S. Pat. No. 7,515,953 discloses a method for detecting fluorescence emitted by cells in a wall of a body lumen, such as an intestinal wall, the method comprising use of a swallowable capsule, the capsule comprising a light source and a fluorescent-labeled probe, which is released from a reservoir in the capsule. According to the disclosure, an electric field generated from an electrode in the capsule enhances uptake of the probe, and a detector in the capsule detects the fluorescent signal emitted. By determining the intensity and/or position in the lumen wall of the fluorescent signal, a drug for killing abnormal cells is released from a second reservoir in the capsule. According to the disclosure, the abnormal cells may be cancer cells, colon polyps or precancerous cells.
U.S. Patent Application Publication No. 2008/0146896 discloses a device, such as an autonomous capsule, for in vivo analysis which includes a reaction chamber to store a detecting reagent able to react with a sample collected in vivo; and optionally a labeled-substance chamber to store a labeled substance able to bind to a compound resulting from a reaction of the detecting reagent and the sample. According to the disclosure, the detecting reagent may be an antibody.
U.S. Patent Application Publication No. 2009/0216082 discloses a device system for in vivo detection of target molecules in an endo-luminal sample, and a method for in vivo magnetic immunoassay, which may be used for the detection of cancer in the gastrointestinal tract.
Yet other methods of colon cancer detection are based on detection of particular proteins or genes which are considered to be specifically or differentially expressed in colon cancer.
U.S. Pat. No. 7,507,541 discloses a method of detecting the presence of inter alia colon cancer that is based on determining the level of 36P6D5 protein expressed by cells in a test tissue sample from an individual, and comparing the level to that expressed in a corresponding normal tissue sample.
U.S. Pat. No. 7,501,242 discloses a method of detecting colon cancer that is based on detecting levels of expression of tyrosine threonine kinase (TTK) in a test sample, such as a colon sample, that are increased by at least two fold relative to the level of expression in a normal non-cancer sample of the same type.
U.S. Pat. No. 7,452,727 discloses a automatable method for identifying cancer cells and their precursor cells that is based on detecting at least two molecular markers, wherein the detection of each marker alone is not a reliable indicator of the presence of cancer cells and their precursor cells. According to the disclosure, the molecular markers may be selected from her2/neu, Ki67, p53, her2/neu, bcl-2, MN, mdm-2, EGF receptor, bcl-2 and p16.
U.S. Pat. No. 7,402,403 discloses a method for the detection of cancer or early neoplastic change that is based on detecting autoantibodies directed to tumor marker antigens in a sample of bodily fluids, wherein the tumor marker antigens are selected from MUC1, p53, c-erbB2, Ras, c-myc, BRCA1, BRCA2, PSA, APC and CA125.
U.S. Pat. No. 7,129,043 discloses a method of identifying a human subject having an increased risk of developing colon cancer that is based on detecting upregulation of the CLN3 gene.
U.S. Pat. No. 7,115,368 relates to a method of detecting epithelial cancer cells inter alia colon cancer that is based on detection of expression in a biological sample of pellino proteins.
U.S. Pat. No. 7,098,008 relates to a method for detection of cancer inter alia colon cancer that is based on detecting expression of melanoma antigen gene (MAGE).
U.S. Pat. No. 7,078,180 relates to a method of diagnosing a cancer inter alia colon cancer that is based on detection of a ZEB (zfh-1/delta EF1) polypeptide.
U.S. Pat. No. 6,949,339 relates to methods for detecting, diagnosing, monitoring, staging, and prognosticating colon cancers, based on detection of Colon Specific Genes.
U.S. Pat. No. 6,919,176 discloses a method of detecting cancer inter alia colon cancer that is based on detection of expression of specific G-protein coupled receptors.
There remains an unmet need for methods of early detection, prognosis and treatment of colon cancer.